Need to replace a 2' fluorescent strip above kitchen sink. The old lamp was mounted right over a 2x3xsomething box and the wires were brought from the box through the knockout on top and the fixture was attached to the ceiling not the box.

Can I replace it in a similar fashion?

Can the connections be made inside the fixture rather than the box?

 

Most florescent fixtures are rated for use as a junction box so no problem.

 

The raw edges of a knockout will cut the wire insulation and needs to be bushed. Most electricians would use a chase nipple in the knockout.

 

Thanks. That would have been fine until I see the new fixture says to only use 90c wires, I have 60c. On the fixture it says make sure supply connections are ratedfor 90. In the manual though it says if the wiring is within 3" from the ballast to use 90c wire.....

Since it doesn't have to be centered, I can probably mount it on one the knockout farthest from the ballast. However, my 60 c wire would be inside the enclosure....

What should I do in this case?

 

Splice 90° to the 60° wire in the box and run the 90° wire into the fixture. Probably overkill but if you have a junk ceiling light cut an insert for the junction box from the fiberglass pad on the back of the junk ceiling light.

 

I should say the new light is a 18" 1x 15watt T8 strip. It has 1/2 knockouts center left and right...

On the inside it says supply connections need to be 90c wire. In manual it says to use 90c if within 3" of ballast.

I assume the ballast will fry the old wiring?

As far as capping it off until I can sort this out, inside the box the old light return was bundled with 3 other white wires. The hot was connected to a switch leg. Is it alright to wire nut the 3 neutrals and the 1 switch leg and leave it off that way?

 

I think you were writing as my post was appearing. Did you see it?

 

Yes I saw it... theres no insulation to cut out for the box.... if I do that it will have to go thru the knockout with a bushing.

Its gotten a lot more technical.

Im realizing this box is part of a mwbc, theres hots from two different circuits spliced in the back of it. There are 3 neutral wires... ones comes from another light, the other two I believe is the return path of the mwbc..... The fixture wire was spliced to them.

 

Insulation probably isn't needed. Just splice new 90° wires on in the junction box and run the new wires into the light. The fixture will cover and shield the old wires in the box.

 

Well thanks, but my problem is now bigger than insulation ratings. Its a MWBC. Adding additional pigtails to the box in the ceiling is going to push the capacity limits. I can add a handy box extension flush with the ceiling for space , mount the fixture right next to it connected to the handybox but is it a good idea to have fixture wires or pigtails for fixture wires connected with the pertinent neutral of a MWBC?

 

I know from the panel that this is part of MWBC.... there are hots from different circuits in this box.

But how do I know for certain that 2 of 3 of the neutrals connected to the old fixture was the return?


also-
another idea could be to mount a box extension flush with the ceiling. The only thing that fits the small device box that I have on hand was a handybox cover. I was thinking I could possibly mount an outlet and use a plug in fluorescent. However, its directly above the kitchen sink so it would have to be gfci and I don't think it would fit in a handybox.

Does it sound like I am over my head or what?

 

I forgot in the first post you wrote: But it should have been a 3" or 4" ceiling box* so my original answer was based on having the correct box not what you have. Can you replace the box? Can you access the space above the box. Or is the light too narrow to cover a ceiling box? If so replace the existing box with a deep old work box.


*Octagon or round.

 

yeah ideally, this is a 60 year old installation. All the outlet boxes are this size (its a 3x2x2 I believe, its a switch box I assume). Theres octagon ceiling boxes in all the rooms but this is not cenetered, its above a sink. And no replacing the box is not practical. I would have been able to easily mount the strip light over the box, add a bushing and bring the wires into the fixture if it wasn't for that 90C wire requirement.... I went back to the store and could not find another fixture that doesn't require this..... that's at home depot, menards and lowes.

What extension options do I have for a small device box like I mentioned?

In the meantime, I put on a handybox extension and capped the switch leg until I can work this out. I have a wirenut on it, if that switch gets turned on accidently, is that a safety concern? The fixture neutral was bundled with 3 others. They were already twisted so I just put on a new wirenut on those. (That's the MWBC im concerned about).


Venture a guess about my other inquiries?

 

Sorry to belabor a point but why? With the exception of brick walls and concrete ceilings I'm having a hard time imaging why.

 

You have some time to replace the box for me Ray?

I'll show you where the attic door is if you want to try to get it above. You would have to snake your way into the narrowest portion by the eaves and dig into the blown in insulation, then the old fiberglass under that to find access. At that point your going to have to cut into the bypass in the ceiling. the box should be recessed into it. You can do all this work on your belly laying on a plank of wood and a ceiling joists or two.

Or we can tear it apart from below perhaps and I can ask in another section about the best ways to repair plaster. Then I have an excuse to break out all my painting equipment, which I just used in that same kitchen last year.

Seeing this is a 10 dollar fixture im not sure that is the route I want to take.

 

First I'd score around the box with a Dremmel*, chop a slot with a thin cheap wood chisel, then I'd cut the box out with a Sawzall using a no teeth carbide coated blade but I haven't worked much with plaster so I'm probably wrong.

*You'd have to use the extra heavy duty carbide disks and probably use up eight or more.

 

10 dollar fixture Ray, I don't think im interested such an undertaking.... I guess this thread has taken a detour....

 

sorry some times I rhink outside the box and need to be reeled in. A wire mold extension box might work.

 

I think I may cut a short piece of conduit and connect it to the handybox extension and the other end to the SIDE of the strip light. I would mount the striplight next to the handybox... no concern about overheating then.

Is that acceptable?

I would make the connections to 90c wire in the handybox extension and then make the usual connections in the fixture.

My only concern now is connecting the pigtail/fixture wire to a tightly wirenutted and twisted group of multi wire branch neutrals. I don't want to break that connection to add a fixture wire and end up making a mistake and cutting them to short while trying to get a splice I am happy with.... that's what I have been on the fence about all day.

 

This is one of those judgement calls. Some heat shrink tubing is rated for 90°. I might just put heat shrink tubing on the existing insulation to protect it but I can't say if it would be code compliant.

 

How is it hooking up the fixture neutral with the wirenutted returns in the box doesn't overheat the smaller fixture wire?

Also pigtailing from the handybox into the fixture... should I use 12AWG (same as the wiring in the box) or to make the splice easier, can I use smaller guage stranded to connect to the 18AWG solid that is in the fixture?

No bones about, I appreciate all advice I get here. I want to square this away ASAP so I don't spend another 8 hours on this tomorrow.

 

All wire before the fixture wire must be sized to the breaker size. Fixture wire can be smaller because of the insulation thermal properties.

 

The light over the sink does not require GFI protection.

 

The fixture wire is designed, made and rated to safely supply the load of the fixture and stand up to standard operating conditions, including ambient heat.

12AWG on a 20A circuit; 14AWG on a 15A circuit.

If you have to turn off two different circuit breakers to kill all of the power in the box, then you have two circuits feeding it. If each of those circuits is also fed with its own neutral, then you have two separate and complete circuits.

If the two ungrounded conductors (hot wires) are sharing one grounded conductor (neutral wire), then (and only then) you have a MWBC.

I'm guessing that one of the cables in the box is a switch leg or switch loop.

As far as wiring up the fixture goes, I'd run the pieces of new wire into the fixture through a cable connector mounted in the center KO. I'd leave - or add on - a 2" or so bit of cable jacket for squeezing in the clamp. I'd tighten the clamp, make the connections and mount the fixture.

 

I ended up mounting a box extension on top of the box. It sits flush with ceiling and connected the fixture to the box with a short piece/nipple of emt thru the side knockout of the box extension. I used set screw connectors on the box extension and the fixture. It works for the space its in.

I should have asked here before doing that though.

Is it ok to come out of a knockout of a box extension like that?




I understand that in regards to heat but I was referring to the fixture neutral being in the same splice as the neutrals for the rest of the circuit. Why isn't the return load from the rest of the circuit too heavy for the fixture wire?

 

Because it doesn't run though the fixture wire. Only the fixture load runs through the fixture wire.

 

You people are making this into a Federal Project . !!! I could have done the fixture in a lot less time than you all have spent talking about it . :-(

Your ballast wires are 90 degree wires , if they are long enough , put a chase nipple and lock nut in the 1/2" KO and wire nut them to the same wires ( in the box ) as feed the old fixture . If the ballast wires are not long enough , go to Home Depot and byu a few feet of white and maybe black THHN . # 12 or # 14 copper . Technically , since it could be considered fixture wire , I think you can go down to # 18 . Or use the size and color of the wires you connect to in the box . Just use THHN insulated wires , it is 90 degree .

God bless
Wyr

 

Good for you, you should advertise in the classifieds.

Your assuming its as easy as white to white black to black. Theres questions I had that go beyond just hooking up the fixture or the temperature rating of the wire.

p.s.- fixture/ballast wire is rated more than 90 degree. And I believe this fixture is intended to bring the house conductors into the fixture rather than the 18awg into the box like your suggesting.

 

Is it OK to extend a circuit out of a knockout of a box extension? Like surface mount wiring.

 

I have no need to advertize in the classifieds , I have a day job & do not do side jobs ( except for myself , or possibly free work for family) .

No telling how many hundreds of light fixtures I have wired and hooked up ?

After the temperature question is resolved , it comes down , precisely to hooking the new light fixture to the 2 wires the old light fixture was hooked up to . If there is an earth ground in the box , run a ground to the new fixture . If not , you can't .

This is not rocket science .

Best wishes
Wyr
God bless

 

Is it OK to extend a circuit out of a knockout of a box extension? Like surface mount wiring.






Yes , it may or may not look pretty , but just use a bushing or chase nipple to protect the wire from sharp edges .

God bless
Wyr